Rust protective lubricants



' Patented Sept. '6, 1949 BUST PROTECTIVE LUBRICANTS George Hugo von Fuchs, Wood River, and Get! hard P. Pilz, Alton, 11]., assignora to Shell Dcvelopment Company, San Francisco, Calif, a corporationof Delaware No Drawing.

Application September 27; 1846. Serial No. 699,644

7 Claims. (CL 252-48-6) The present invention relates to compositions having anti-corrosive, and especially rust-protective properties. More particularly, it deals with compositions comprising certain esters of polybasic organic acids containing a minor amount of organic acid-acting materials which are highly effective corrosion inhibitors when used in combination with such esters.

Metallic surfaces, particularly those containing iron, require protection against corrosion in the presence of water. To illustrate: Moisture readily attacks finished or semi-finished metal objects unless the metal surface is covered during storage or shipment by a protective coating such as a slushing oil; water in engine lubricants often corrodes closely fitted engine parts such as found in Diesel engines; water in turbines corrodes turbine lubricant circulatory systems, particularly the governor mechanisms of steam turbines.

Corrosion not only has a deleterious effect upon the metal surfaces, but also frequently forms finely divided metal oxides which may act as oxidation catalysts, increasing the rate of deterioration of various organic compounds with which they come in contact, or may enter between moving parts of machinery where they act as abrasives.

It is an object of this invention to provide eflective corrosion-protective compositions of wide applicability. Another object of this invention is to produce lubricant oils and greases having improved corrosion-protective properties. A specific purpose of this invention is to produce rust-protective compositions comprising as the major lubricating base, esters of poly-basic organic acids as more particularly defined hereinafter.

The corrosion and rust problems involved when using compositions comprising these esters difler considerably from those which must be met when mineral oil lubricants areemployed. In the latter case, the mineral oils, being substantially completely immiscible with water, have no tendency to absorb moisture from the surrounding atmosphere. The esters on the other hand, absorb moisture to an appreciable extent, thus promoting intimate contact between the latter and the metal being lubricated by them. Corrosion is thus promoted by the ordinary use of esters as lubricants, rather than discouraged, as in the case of mineral oils.

Moreover, the class of esters described herein, being of relatively high molecular weight, inherently act as protective colloids, and thereby maskthe action of most of the ordinary rust inhibitors useful in mineral oil compositions. Consequently, 56

while amounts of 0.001% to 0.1% of an inhibitor may provide excellent rust prevention in a mineral oil base composition, like compositions based upon the subject esters are unsatisfactory from the stand-point of rusting, and corrosion.

Up to the present time. while certain esters of polybasic-organic acids have found use as lubricants, no suitable means has been found for making such substances rust-resistant, this in spite of the extensive disclosure and knowledge of various rust inhibitors for minera1 oil lubricants.

Now, in accordance with this invention, it has been found that lubricating compositions comprising predominantly esters of polybasic organic acids having the general formula coonrl 4- I RI Ldoonnl.

wherein n is an integer. R1, R1 and Rs are organic radicals (especially hydrocarbon radicals) having more than two carbon atoms, and R4 and R5 are substituents such as hydrogens or organic radicals (especially hydrocarbon radicals), may be made substantially rust-protective by the inclusion or incorporation of a minor amount of an organic acid acting material capable of forming water-insoluble metallic soaps. Preferably, the acid is insoluble in water.

Further, in accordance with this invention, it has been found that the action of such acidic materials as rust inhibitors is promoted by the addition of a small amount of salts and esters of monobasic organic acids.

The subject ester lubricants include both monomers and polymers. Preferably, especially when the esters are to be used as the principal ingredients of lubricating compositions they have a high viscosity index and a low pour point. Alternatively, the consistency, Pour point, etc., may be suitably modified by the addition of thickeners, or other agents affecting the properties of the esters. The esters which meet these conditions most satisfactorily are those in which R1 is a hydrocarbon radical having from 4 to 12 carbon atoms, while those in which R1 is a hydrocarbon of 4 to 8 carbon atoms give the best over-all results. of this group, those in which R1 is a saturated aliphatic radical are the most stable, although unsaturated radicals of either olefinic or aromatic character form esters which also are suitable for use as lubricant base.

The monomers of preferred structure are those in which R1 is a saturated aliphatic radical having less than 2 side chains. These are the esters of dicarboxylic acids, theoretically formed by the replacement of 2 hydrosens of a saturated hydrocarbon with two ester groups. Those in which the ester groups are terminals on opposite ends of the molecule form excellent lubricants, especially when R; has from 4 to 8 carbon atoms. These include the esters of acids having the general formula C 0 r a-Bl isomers, anrvlglutaric acid and its isomers, di-

methylglutaric acid, methylethylglutaric acid, methylpropylglutaric acid, methylbutylglutaric acid' and its isomers, diethylglutaric acid, and ethylpropylglutaric acid. I

When R1 contains 4 carbons in a straight c the esters are based upon the adipic acid series, such as adipic acid, 2-methyladipic acid, 2-ethyladipic acid, z-propyladipic acids, 2-butyladipic acids, 2,2-dimethyladipic acid, 2,3-dimethyladipic acid, 2-methyl-2-ethyladipic acid, 2-methyl-3- ethyladipic acid, 2-methyl-2-isopropyladipic acid, etc.

The esters of pimelic acid derivatives, in which Rs contains a straight chain of 5 carbon atoms, also fall within this preferred group. These esters are formed from such acids as pimelic acid, 2- or 3-methylpimelic acid, 2- or 3-ethylpimelic acid, 2- or 3-propylpimelic acid, 2- or 3-isopropylpimelic acid, 2,2- or 2,3-dimethylpimelic acid, or 2-methyl-2-ethylpimelic acid, 2-methyl-3-ethylpimelic acid, 3-methyl-3-ethylpimelicacid, 2-

ethyl-3-methylpimelic acid, 2,2,3-trimethylplmelic acid; 2,3,4-trimethylpimelic acid, etc.

If the group R1 has a straight chain of 6 carbon atoms, the esters then are derived from suberic acid, including suberic acid itself, methylor ethylsuberic acids, in which the methyl or ethyl groups may be in positions 2,3,4 or 5; and methylethylsuberic acids, wherein the methyl and ethyl groups are in positions 2,3,4 or 5. When R1 either has 7 or 8 carbon atoms in a straight chain, the esters are based upon azelaic acid, methylazelaic acids, or sebacic acid.

While esters based upon the above acids are preferred. higher acids are useful for special purposes. In such cases R1 may be a straight or branched chain, but preferably is a saturated aliphatic hydrocarbon radical.

Other useful esters are derived from acids in which R1 is represented by the general formula l to give esters of the general formula I inwhichnisanintegenRaRsmandnlare organic radicals (preferably hydrocarbon radicals), R4 and Rs are either hydrogen or organic radicals and X is oxygen, sulfur, selenium, tellurium or nitrogen. When esters of dibasic acids of this type form the base of the corrosion protective composition, it is preferred that X is oxygen, sulfur or nitrogen, 12 is -1, R4 and Rs are hydrogens and Re and R1 are similar or dissimilar (the former is preferred) saturated hydrocarbon radicals, each having from 2 to 20 carbon atoms.

Hence, acids of the above type include the preferred general types of esters:

000a coon (A 1) Hz)" Esters of type A are derived from such acids as alpha, alpha'-dilauric, dimyristic, dipalmitic, distearic, diarachic and dioleic acid ethers. They are produced, for example, by reacting the diand alkali salt of an alpha-hydroxy carboxylic acid with an alphaor beta-monochloro or monobromo fatty acid. The two substituents attached to the oxygen atom may be similar or dissimilar, preferably the former. The acid ether thus formed is then esterifled to give the base for the compositions of the present invention. Formula type B above includes esters of acid thioethers such as alpha, alpha'- myristic, palmitic, stearic, arachic behenic acid sulfides. Type C esters are preferably tertiary amine derivatives, especially when they are anilino, toluidino or xylidino dialpha fatty acid esters.

Two other types of esters comprise suitable bases for the subject corrosion-protective compositions. These have the general formulas:

Rr-COORr 1i. i fir-C 0 0B;

C 0 OR.

[R x r ll-"( (Typ and

preferably 1, and n is an integer which is at least 1 and never greater than m. Unoccupied valences may be tied to the same or different hydrogen or hydrocarbon radicals. Esters of this type include, for example, those derived from alphabeta dilauryl dithio succinic acid and monothio lauryl succinic acid.

When n in the general formula I'COOR Ltoonj,

l-lOOChHu (BOOC'IHitand polyvinyl pelargonate:

CH-CHFCH-Cfll Lt: O CiHu (50 O CsHn-L The esterifying radicals attached to the subject dicarboxylic acids may be similar or dissimilar, but preferably are the former. While any organic esterifying group is suitable, those in which R: and R: of the ester groups-(300R: and 000R: are hydrocarbons are preferred; when R: and R: are saturated hydrocarbons, the resulting esters have the most satisfactory stability toward oxidation; and when R: and R3 are aliphatic groups having at least 2, preferably from 4 to 20, carbon atoms, the resulting ester has optimum lubricating properties. The best esters for lubricating purposes are those having the general configuration C O O R:

Ltoonnl.

in which 11. is preferably 1, R1 together with R4 and Rs form a saturated hydrocarbon radical preferably having from 4 to 12 carbon atoms and R2 and Rs are preferably similar saturated hydrocarbon radicals having from 4 to 20 carbon atoms. However, as pointed out hereinbefore, polymers, 1. e. wherein n is more than 1, also are suitable lubricants and anti-corrosion bases, especially when R2 and R3 have from 4 to 20 carbon atoms.

When R2 and R3 have the preferred configuration i. e. similar saturated hydrocarbon radicals having from 4 to 20 carbon atoms, the latter may have the aliphatic or allcyclic configurations, but preferably are aliphatic. In this case they are either straight or branched chain radicals, but those having less than 3 substituents replacing hydrogens of a straight chain are preferred because of the superior properties of the esters formed therefrom. Consequently, R: and Rs are radicals theoretically derived from such hydrocarbons as butane, 1,1-dimethylethane, 1,2-dimethylethane, pentane, 2- or S-methylbutane, 2- or 3-ethylpropane, 2,2- or 2,3-dimethylpropane,

hexane, 2-, 3- or 4-methylpentane, 2,2-dlmethylbutane, 2.3-dimethylbutane, z-ethylbutane, 3- or 4-ethylbutane, 2-methyl-3-ethylpropane; 2,3-diisopropylethane; 3,4-diethylbutane. heptane, 3- amylpropane, 2-, 3-, 4-, or S-methylhexane; 2-, 3-, or *i-ethylpentane; 2,3-diethylpropane: 3,3-di propylethane, octane; 2-, 3-, or i-ethylhexane. 2-, 3-, -butylbutane; 2,2-dimethylhexane, 3,3- djmethylhexane, nonane, 3,3-diethylpentane, 2- ethyl 3 methylhexane, 2 isopropyl 4 butyloctane; 3,6-dibutylhexane, 2-butyl-5-ethylhexyloctane; and their homologs, analogs and derivatives.

Compounds falling within the general formula characterizing the esters of the present invention include, for example, Z-methyiheptyl adipate, B-ethylhexyl adipate, dioctyl phthalate, dihexyl pimelate, 3-methy1heptyl pimelate, 3,3-diisopropylhexyl pimelate, 2-ethylhexyl sebacate, polyallyl pelargonate, polyallyl caprylate, polyvinyl pelargonate, polyvinyl caprylate, as well as their homologs, analogs, and derivatives.

The organic acidic substances with which the subject esters are combined to comprise the compositions of this invention are of great variety. their only qualifications being that they exhibit acidic reactions in the environment in which the compositions are to be used and that they be capable of forming water insoluble metallic soaps. Preferably, they are substantially water-insoluble acids. Preferably, also the metallic soaps formed by the acids are. insoluble in the lubricant and do not readily hydrolyze or oxidize. They include, among others, the following preferred classes of organic acidic materials:

(a) Water-insoluble aliphatic monocarboxylic acids (b) Water-insoluble acids (0) Partial esters of poLvvalent acids (d) Water-insoluble aromatic carboxylic acids (6) Organic sulfonic acids aliphatic polycarboxylic '(f) Organic resinous materials containing acidic groups where R is an aliphatic radical of either paraffinic, olefinic or acetylenic character.

The saturated fatty acids falling within the class include, among others, valeric, caproic, enanthylic, caprylic, pelargonic, capric, undecylic, lauric, tridecoic, myristlc, petadecanoic, palmitic, margaric, stearic, carnaubic, cerotic and psyllic acids.

When the compositions of this invention containing the organic acidic material are to be used for purposes where heat will be encountered,

7 such as in engine lubrication, the acid must be of such character that it will not volatilize under the conditions of use. In such case, where a material having saturated fatty acid characteristics is involved, the series of operable acids correspond to the formula where R1 is a saturated aliphatic radical having 6 or more carbon atoms and preferably is an acid having 10 or more carbon atoms. Of this group lauric acid gives excellent rust-inhibiting results.

The mono-oleflnic acids which constitute rustinhibitors for the polymeric compositions are of the general formula where R; is a mono-olefinic radical having two or more carbon atoms. These include acrylic, methacrylic, -di-methacrylic, crotonic, isocrotonic, and vinylacetic; pentenic acids such as tiglic, angelic and senecioic acids, hexenic, teracrylic, hypogeic, oleic, elaidic, erucic and behenic acids.

When the compositions are to be employed for purposes where undue heating is not expected, the lower mono-olefinic acids, such as methacrylic, -dimethacrylic, etc. provide as satisfactory rust inhibition as those of higher boiling point and greater molecular weight. On the other hand, when the polymeric compositions are to be subjected to elevated temperatures, the rust, inhibiting acidic material should conform to the general formula Bri -OH where R: is a mono-oleflnic radical containing at least 6 carbon atoms, and preferably contains or more carbon atoms. Of this latter group oleic acid and various substitution and addition products thereof is outstanding in its rust-in hibition action in the subject polymeric compositions.

Dioleflnic, polyolefinic and acetylenic acids act as rust inhibitors for the oil-like esters herein described. Among such acids suitable for rust inhibition are sorbic, linoleic, linolenic acids; propiolic, z-butyonic, z-pentynoic, amylpropiolic, palmitolic and stearolic acid. Of this group of unsaturated acids. linoleic and linolenic acids give superior rust inhibition.

The dibasic aliphatic acids may be used in corrosion preventive ester lubricant compositions. For example, the oxalic acid series of acids give satisfactory results. This class of acids is represented by malonic, succinic, glutaric, adipic, pimelic, and sebacic acids. The acids of this class which are particularly useful in carrying out the present invention are those having four or more carbon atoms in the aliphatic group, and preferably those having at least seven The unsaturated aliphatic dibasic acids likewise may be employed in rust-protective ester lubricant compositions. These include the fumaric acids, such as maleic, glutaconic, propylidenemalonic, allylsuccinic and cetylmalonic acids; and acetylenedicarboxylic acids such as butenedioic acid. When using unsaturated aliphatic dicarboxylic acids as rust-inhibitors, those having at least four carbon atoms in the aliphatic radical give satisfactory results, but the higher acids, having fifteen or more carbon atoms are preferred.

The aromatic monoand di-carboxylic acids, when combined with the ester-type lubricating bases, form rust-inhibiting compositions suitable for general use. These acids all have boiling points high enough to prevent substantial vaporization at temperatures normally encountered in engine lubrication, such as in oils and greases, but those having ten or more carbon atoms in the aromatic radical are especially suitable. Among the aromatic carboxylic acids useful in the polymeric compositions are benzoic, phenylacetic, mesitylic, phthalic and cumidinic acids.

Mixtures of acids found in natural products are also suitable as rust-inhibitors, such as the acids from linseed oil, rape seed oil, cottonseed oil, soya bean oil, corn oil, rice oil, sesame oil, mustard seed oil, etc.

Other types of acids which may be employed as rust-inhibitors for lubricating esters are hydroxy acids, ketonic acids, amino acids, sulfonic acids, including those derived from petroleum fractions, and thiocarbonic acids, as well as the resin acids, containing carboxyls or other free acid groups. While the lower members of these series exhibit rust-inhibiting properties when present in the polymeric compositions, the most satisfactory results are obtained from acids having four or more carbon atoms in the molecule, in addition to any in the acid radical itself. Those having ten -or more carbon atoms are preferred, since they give optimum protection, and are readily soluble in the esters,

The various'acids of the types listed above may contain substitution groups or radicals which increase their effectiveness, solubility or other properties in the ester compositions. Acids of this type which have outstanding rust-inhibiting properties for the present use include the reaction products of sulfur and an unsaturated fatty acid, such, for example, as oleic acid. Another type of product which is especially useful for rust-inhibition is obtained by the condensation of oleflnes with a polybasic acid anhydride, such as maleic anhydride. These alkenyl carboxylic acids, such as the octadecenyl succinic acids, have excellent rust-inhibiting properties when used in conjunction with the esters described hereinbefore. In order to prevent undue loss under conditions encountered during use, these two latter types of acids should have aliphatic radicals of four or more carbon atoms, and preferably more than ten carbon atoms.

Among the partially esterified acids which are excellent rust-inhibitors are the monoand diesters of phosphoric acid. Of this group of acids monoand di-fatty alkylated derivatives of substantial molecular weight are especially satisfactory, such as the monoand di-lauryl phosphates shown in Table I later in this specification. When partial esters are the rust-inhibiting component of the composition, they should have more than three carbon atoms in at least one of the albl groups, and preferably one of the alkyl groups has at least ten carbon atoms.

The amounts of the rust-inhibiting acids which must be incorporated to produce rust-protective compositions vary considerably with the identity of the inhibiting acid and type of lubricating ester employed. In the absence of materials substantially masking the rust-inhibiting effects of the acids in such compositions, the amount required of acidic material vary from about 0.5% to about 6%, although greater amounts may be used.

However, if an excessive amount of organic acidic material is added to the ester composition, the latter loses its proper lubricating qualities which make it suitable as an engine or machine lubricant. Preferably the amount of acidic material in the composition will be from about 1% to about 4%, since optimum-rust-inhibition occurs within this range. If the acid is present as a colloidal dispersion, rather than as a true solution, allowance for settling must be made. Since the higher molecular weight lubricating esters may act more or less as protective colloids, and in themselves act as suspending agents, undue settling does not ordinarily occur when care is taken to effect proper initial dispersion.

To produce the anti-corrosive compositions, the acid is finely dispersed in the oil-like ester base. The dispersion may be a true or colloidal solution. True solutions are in general preferred whenever they can possibly be obtained, since a colloid may precipitate, in which case at least a portion of the active ingredient is removed.

As stated hereinbefore, another novel feature of this invention is the addition of salts and esters of monobasic organic acids to the corrosion protective compositions comprising the subject lubricating esters of dicarboxylic acids and rustinhibiting organic acids. Preferably, the monobasic organic acids from which the salts and esters are derived are either monocarboxylic or monosulionic acids. The exact function of the salts and esters of monobasic organic acid in the present compositions is not clear. All that is evident is that addition of such materials to compositions of the present invention enhances the corrosion protectiveness of the compositions.

The monobasic hydrocarbon sulfonic acids from which these salts and esters are derived are preferably obtained in the treatment of relatively heavy mineral oils, such as the so-called paramnic oils, includin Pennsylvania and Mid-Continent gas oils or lubricating oils. with concentrated or fuming sulfuric acid. In this kind of treatment two kinds of acids, namely, so-called green acids and mahogany acids are formed. The salts and esters of mahogany acids are most effective in enhancing the corrosion-protective properties of the present invention, but green acids also are effective promoters for the present compositions. These acids constitute complicatedmixtures of many diflerent hydrocarbon sulfonic acids, many of which are believed to be 01' aromatic character, although others are probably of naphthenic and aliphatic origin. They are specified herein as petroleum sulfonic acids.

Other hydrocarbon sulfonic acids suitable for the preparation of the salts and esters which act as promoters or boosters for the anticorrosion properties of the present compositions are produced for example by sulfonating alkyl aromatic hydrocarbons such as alkyl benzenes, alkyl naphthalenes, alkyl anthracenes, alkyl picenes, alkyl chrysenes, alkyl diphenyls, etc., provided the alkyl substituents are such as to render the esters and salts of the sulfonic acid soluble or at least dispersible in the compositions of the present invention. It is desirable that at least one alkyl radical be relatively long, i. e., containing at least 8 carbon atoms, since salts and esters of sulfonic acids containing alkyl groups of this character are the best anti-corrosion promoters for the present compositions.

The hydrocarbon sulfonic acids may, if desired, contain substitution radicals, such as hydroxvl, primary, secondary or tertiary amine, ether, sul- 10 fide, hydrosulfled. disulfled, halogen etc. radicals which may be attached to a ring or a side chain or both.

The salts of the suli'onic acids preferably are formed from polyvalent metals, particularly the light-weight metals such as Mg, Ca, Sr, Ba, Al and Zn. However, other polyvalent metals may be used, particularly those having only one oxide, or one of several oxides which is more stable than and is not readily convertible to the others under ordinary lubrication conditions in internal combustion engines, such as Cd, Sn, Co, Ni, etc.

Suitable monocarboxylic acid esters and salts are those of such acids as lauric. stearic, oleic, arachic, behenic, ricinoleic acids, naphthenic acids, wool fat acids, tall oil derivatives, alkylbenzoic acids, naphthoic acid, phenylacetic acid, especially when the acid has at least 7 and preferably 10 to 30 carbon atoms.

The alcohol with which the acid is esterfled is either monohydric or polyhydric, but the esters having optimum anti-corrosion promoting properties in the present compositions are those in which the esterlfying alcohol has three or more hydroxyl groups, preferably from three to eight. Such alcohols include glycerol, erythritol, arabitol, mannitol, sorbitol, quinteryl glycerin, diethyl glycerol, mesicerin, perseitol, their isomers, homologs, analogs, substituted derivatives. etc.

The outstanding esters of the monocarboxylic acids for use in the present invention are those derived from the reaction of higher fatty acids with alcohols having from' three to six hydroxyl groups. These include, for example, glycerol monooleate, dioleate and trioleate; glycerol monostearate, distearate and tristearate; glycerol monolaurate, dilaurate and trilaurate; sorbitol monooleate, mannitol monooleate, sorbitol monolaurate, mannitol monolaurate, etc. The mono esters are preferred, since they give optimumresults as anti-corrosion promoters for the compositions of this invention.

When-the salts and esters of monobasic or ganic acids are added to the compositions of the present invention, they may be present in amounts from about 0.25% to about 5% by weight of the composition. Preferably, they are employed in amounts less than that of the free, rustinhibiting organic acid also present in the composition. Optimum results are obtained when the proportion of salt or ester is from about 0.3 to about 2.5% by weight of the total composition.

Applications of the various corrosion-protective compositions vary over a wide range. For example, cans, drums or tanks of the esters may cause severe rusting due to accumulation and adsorption of water. This is particularly bad in tropical countries where the moisture content of the air is high, and wide variations in temperature over a 24-hour cycle cause considerable breathing of the containers. However, the

compositions of this invention substantially pre- This is of par-.

Cutting oils, comprising various lubricating esters, due to their content or additives in active form, frequently are quite corrosive. The monocarboxylic acids specified hereinbeiore when added to the ester lubricant inhibit this corrosion.

It is understood that the corrosion-protective compositions of this invention may contain other ingredients in addition to the ester bases and the specified organic acids. However, such additional ingredients should be substantially chemically inert to the acids employed unless, by their action, they improve the corrosion-inhibiting properties of the composition. Thus, strong bases, particularly in the presence or moisture, will neutralize the acids and tend to render them less effective. However, the presence of small amounts of primary. secondary or tertiary nitrogen bases will not normally interfere with the activity or the rust-inhibitor.

Accordingly, compositions of the oil-like ester bases and the organic acids may contain various types of oxidation inhibitors, E. P. agents. pour point depressants, anti-wear compounds, detergents, sludge-preventing compounds and so on.

The examples given below are illustrative of the beneficial effects of this invention, but are not to be understood as limiting the invention specifically thereto.

A lubricant consisting essentially of z-ethylhexyl sebacate was used as the base in the following tests. Table I lists various acidic rustinhibitors added to portions thereof, and the percentage by weight in which they were used.

Sand-blasted strips of steel were dipped in the compositions for one minute at room temperature, removed and allowed to drain for 20 hours at 130 F. and then hung in a cabinet at 100 F'., the atmosphere of the cabinet being maintained at 100% relative humidity for that temperature until 10% of the surface of the strip had rusted. Table I lists the length of time each composition protected the steel strips from rusting under these conditions:

Table I Weight Per Cent Concentration of Rus Inhibitor Hours Before 10% Busting in Humidity Cabinet Example Bust-Inhibitor No inhibitor Mixture of monoand di laurylphoepbates 2 Mlaixturex 111)! niozzg-s and diuryp osp a ixture oi octadecenyl sucless than 0.1

Laurie acid Similar tests were conducted, using 2-ethylhewl sebacate as the base, and adding thereto acids and promoters of the identity and in the amounts itemized in Tables 11, III and IV. The increase in rust protection of the ternary mixtures over that obtained by similar compositions containin no promoters is emphasized by the ilaufilidity cabinet test results also given in the Table II Promoter For Rust Emit s 111mm Inhibitor m Be on 10% Busting None Nnnn Less than 0.1. 1% Mixed octadecenyl .do 48.

succinic acids.

Do 1%ts0l'blt01 Monocle- 96.

a a. Do 1% glycerol Monocle- 72.

Table III Pro te r Bust Eiit ti? mo l 01' y B Rust Inhibit Inhibitor net Beiore 10% Busting None None Lea than 0.1. 1% Mixed monoand (11- do 48.

laurylphosphutes.

Do 1%teSorbitol Monoole- 144.

8 Do 1%tGlycerol Monoclo- 144.

Table IV Pro to F Bust ml'ft'y b ifi' mo r or a Rust Inhibit"! Inhibitor net Before 10 Busting Nona Nnnn Less than 0 l 0.5 Stearic acid do 5 D 0.3 mixed Calcium salts 432.

(X Petroleum Sullor 10 We claim as our invention: 1. A liquid lubricating composition consisting essentially of a predominating amount of an ester of an aliphatic dicarboxylic acid and of an all-- phatic monohydric alcohol having 2 to 20 carbon atoms and as an anti-corrosion agent therefor from 1% to 4% by weight of an acid of the group consisting of fatty acids having at least 7 carbon atoms, sulfurized unsaturated monocarbonlic acids having at least 7 carbon atoms, and alkyl phosphoric acids having at least 10 carbon atoms in an alkyl substituent.

2. A liquid lubricating composition consisting essentially of a predominating amount of an ester of an aliphatic dicarboxylic acid and of an allphatic monohydric alcohol having 2 to 20 carbon atoms and as an anti-corrosion agent therefor from 1% to 4% by weight of a suliurized unsaturated monocarboxylic acid having at least '7 carbon atoms.

3. A liquid lubricating composition consistin essentially of a predominating amount of an ester of an aliphatic dicarboxylic acid and of an aliphatic monohydric alcohol having 2 to 20 carbon atoms and as an anti-corrosion agent therefor from 1% to 4% by weight of an alkyl phosphoric acid having at least 10 carbon atoms in an alkyl substituent.

4. A liquid lubricating composition consisting essentially of a predominating amount of an ester 01 an aliphatic dicarboxylic acid and of an aliphatic monohydric alcohol having 2 to 20 carbon atoms and as an anti-corrosion agent therefor from 1% to 4% by weight of a fatty acid havin at least 7 carbon atoms.

5. A corrosion-protective composition consisting essentially of a predominant amount of 2- ethylhexyl sebacate and as an anti-corrosion 13 agent therefor from about 1% to about 4% of oleic acid.

6. A corrosion-protective composition consisting essentially of a major amount of 2-ethylhexyl sebacate and as an anti-corrosion agent therefor from about 1% to about 4% of a mixture of monolauryl phosphate and dilauryl phosphate.

7. A corrosion-protective composition consisting essentially of a major amount of 2-ethylhexyl sebacate and as an anti-corrosion agent therefor 10 REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Zimmer Heb. 17, 1948 Duncan Jan. 13, 1948 Wasson Mar. 11, 1947 Sharpe Apr. 9, 1946 Cook May 6, 1942 Schilling Jan. 27, 1942 Rocchini Nov. 4, 1941 Baxter Feb. 14, 1939 Renter Nov. 1, 1938 Benning May 11, 1937 Groves Mar. 12, 1935 

